I have contributed to the following works:

THE GREENWOOD ENCYCLOPEDIA OF SCIENCE FICTION AND FANTASY THEMES, WORKS, AND WONDERS   EDITED BY GARY WESTFAHL

(Greenwood Press, Westport Connecticut, 2005)

CHRISTOPHER PRIEST: THE INTERACTION   EDITED BY ANDREW M. BUTLER

(Foundation Studies in Science Fiction, 6; The Science Fiction Foundation, London, 2005)  'Blank Pages: Islands and Identity in the Fiction of Christopher Priest' – Recommended Reading: BSFA Non-fiction Award, 2006.

SPECULATIONS ON SPECULATION: THEORIES OF SCIENCE FICTION   EDITED BY JAMES GUNN & MATTHEW CANDELARIA

(Scarecrow Press, Lanham, MD, 2005)  My essay 'On the Origins of Genre' was republished here.

ANATOMY OF WONDER: FIFTH EDITION   EDITED BY NEIL BARRON

(Libraries Unlimited, Westport, CA, 2004) 

SUPERNATURAL FICTION WRITERS  EDITED BY RICHARD BLEILER

(Thomson Gale, New York, 2003)

CYCLOPAEDIA OF LITERARY PLACES

(Salem Press, New York, 2003)

THE ENCYCLOPEDIA OF FANTASY   EDITED BY JOHN CLUTE & JOHN GRANT

(Little Brown, London, 1997)

THE ST JAMES GUIDE TO SCIENCE FICTION WRITERS   EDITED BY JAY P. PEDERSON

(St James, Detroit, 1996)

THE MAGILL GUIDE TO SCIENCE FICTION

(Salem Press, New York, 1996)

THE ST JAMES GUIDE TO FANTASY WRITERS   EDITED BY DAVID PRINGLE

(St James Press, Detroit, 1996)

TWENTIETH CENTURY SCIENCE FICTION WRITERS, THIRD EDITION  EDITED BY NOELLE WATSON & PAUL E. SCHELLINGER

(St James Press, Chicago, 1991)

On top of all that, my reviews, articles, interviews, etc, have appeared in: New Scientist, Times Literary Supplement, Literary Review, Good Book Guide, The Fiction Magazine, British Book News, New York Review of Science Fiction, Extrapolation, Foundation, Science Fiction Studies, Journal of the Fantastic in the Arts, Vector, Matrix, Interzone, Steam Engine Time, Strange Horizons, SF Site and a variety of other journals.